It is often necessary to obtain a full view of an object or otherwise establish an optical path to a point without using a direct optical path. For example, an indirect optical path is useful to enable viewing of a radioactive substance by means of visible radiation while at the same time providing a protective screen or block against radiation which is not reflected such as alpha, beta or gamma rays. Another example relates to a deposition chamber where the window, used to view the deposition operation and the object on which the deposition is being made, quickly becomes covered by the deposition action so that the view is blocked. Prior art attempts to circumvent this problem have either used a blocking member to place the viewing window in the shadow of the depositing source or used mirrors in a periscope arrangement. The periscope arrangement relies on the fact that the deposition improves, not detracts from the reflective properties of the mirrors. However, both of these approaches have serious shortcomings. Only a limited number of positions are available from which to make observations. The reflecting and blocking elements require specific placement to afford the proper view and have appreciable size; both considerations diminish the effective utilization of the space within the chamber. The viewing angle is quite narrow and the viewing positions are limited so that a comprehensive view of the entire chamber and contents is difficullt to obtain. Illumination of the chamber interior through a periscope arrangement cannot satisfactorily be done simultaneously with viewing the interior.